C Fastener
  • Westley Richards' proprietary toplever-actuated bolting system for break-open guns and rifles, whereby the toplever, when pushed to the right, cams against a facet on the top of the action body and withdraws the locking bolts rearward from their respective bites.
C Ring
  • An internal web machined in the front receiver ring of a Mauser Model 98 and of all the proper copies of this famous action. Not only does this internal ring provide additional strength to the receiver at its most stress-bearing point, this essential part of the design provides a stop for the barrel when screwed into the receiver, allowing positive control of headspace. Because there is a cut-out for the bolt's claw extractor, it appears in the form of a "C" when viewed from the loading ramp. Being difficult to machine, lesser actions' front receiver rings are simply bored straight through.
Cable Lock
  • A cable with a padlock at the end. It is threaded through the action of the firearm.
Cal or Caliber
  • System of measurement for the internal bore diameter of a rifled-barreled firearm (rifle or pistol) based on the decimal part of an inch. For example, .25 calibre and .250 calibre both signify a bore size of 1/4 inch. American calibre designations refer to the distance from land to land, not groove to groove. Ammunition companies' marketing departments occasionally take liberties with exact measurements. For example, a .270 Winchester bullet actually measures .277 inch in diameter.
Caliber

[kal-uh-ber]

  • The diameter of the bore of a gun taken as a unit of measurement.

  • The diameter of the bore of a firearm measured as a fraction of an inch. Although such a measurement may be frequently stated in millimeters. It is correctly expressed as ".40 caliber" (note the decimal point) or as "10 millimeter" (without "caliber" or the leading decimal point). Caliber numbers when used to identify the size of the bullet a gun will file are usually followed by words or letters to create the complete name of the cartridge. These letters often represent a brand name or an abbreviation for the name of the company that first introduced the round.
Call Bead
  • A flat gold or brass disc, mounted into the face of a front sight, seen as a crisp circle.
Camp Perry

[kamp]  [per-ee]

  • National Guard facility near Port Clinton, Ohio containing the largest rifle range in the world. Site, since 1912 of the NRA's national rifle matches. Also, in its honor, the name of a model of Colt .22LR calibre single shot target pistol.
Can
  • Slang term for a firearm sound suppressor.
Cannelure

[kan-l-oo r]

  • A crimped or knurled groove, rolled onto a bullet or the neck of a cartridge case, to help retain a bullet in its case, and/or to provide a space for bullet lubricant.
  • A groove or indention around the circumference of a bullet. Its purpose is to permit the cartridge casing to be crimped tightly against the bullet shank to hold it firmly to the casing. A groove or indention around the circumference of a bullet. Its purpose is to permit the cartridge casing to be crimped tightly against the bullet shank to hold it firmly to the casing.
Cant

[kant]

  • To tilt a gun to one side or the other, complicating sighting considerably. Can cause material loss of accuracy, particularly with a rifle at longer ranges. Some better long range target rifles are equipped with Spirit Level sights to help the marksman control canting.
  • Tilting the firearm slightly to one side, so the grip is no longer vertical in relation to the ground. Canting the firearm can make precision shooting more difficult, but may be necessary in some circumstances.
Cap

[kap]

  • A percussion cap; a separate primer; fit over the tip of the nipple of a muzzle-loading percussion-actioned firearm.
Cape Gun
  • A two-barreled, side-by-side, shoulder-fired gun having one smoothbore shotgun barrel and one rifled barrel.
Capper De Capper
  • A hand tool used in the field for inserting live and removing spent primers from cartridges.
Captive Ramrod

[kap-tiv]   ˈramˌräd/

  • A rod, for loading and/or cleaning a muzzle-loading firearm (usually a pistol) that is permanently connected to the gun by some sort of swivel, so as to be utilized easily, but never lost.
Carbine

[kahr-been, -bahyn]  

  • A rifle with a relatively short barrel. Any rifle or carbine with a barrel less than 16" long must be registered with the Bureau of Alcohol, Tobacco and Firearms. Shotguns with barrels less than 18" long fall into the same category. Commonly used today to indicate any rifle of short overall length.

  • A general term referring to relatively short-barreled, quick-handling rifle, often intended for use on horseback.

  • In Winchester lever-action terminology, a carbine has a single barrel band.  In German, a Stutzen.
Cartouche

kärˈto͞oSH/

  • A mark within a border. On an American military rifle it is typically stamped into the wood and shows the initials of the name of the accepting inspector and often, the date he accepted the firearm into service. Notable gun makers have used the concept by stamping their mark onto a bit of precious metal in a small recess in the steel.
Cartridge

[kahr-trij]

  • In its definition valid from circa 1870 to the present:  a small usually cylindrical packet, containing a detonating primer, a powder charge, a load---either a single projectile for a rifle or a quantity of small pellets for a shotgun---and possibly some attendant wadding. The cartridge is placed into the breech of a firearm, comprising all required consumables for the firing of the weapon.
  • A single, complete round of ammunition which includes the case, primer, powder, and bullet
Cartridge Trap
  • A compartment built into the buttstock of a long gun, usually with a hinged cover, in which are drilled holes deep enough to hold several spare cartridges of the type suitable for use in the specific gun
Case or Casing

[key-sing]

  • The envelope (container) of a cartridge. For rifles and handguns it is usually of brass or other metal; for shotguns it is usually of paper or plastic with a metal head and is more often called a "shell."
Casehardening Colors

[keys-hahr-dn]  

  • Mottled blue/green/brown colors on a shotgun or double rifle receiver, vintage Winchester receiver or Colt Single Action frame. The colors are the by-product of a heat-treating process that incorporates carbon into the surface molecular structure of the steel, providing a hard-wearing surface without making the entire receiver brittle. The parts to be casehardened are packed in a crucible with carbon-rich media such as bone meal and charcoal, heated to bright orange, about 1800°F, then quenched in bubbling oil. Also called Carbonizing. The colors themselves are fairly perishable both from wear and from sunlight. The percentage of original case colors remaining is therefore a quick proxy for the cosmetic condition of the gun.

 

Guns should never be rehardened in the vain interest of restoring the cosmetic effect of the colors. Casehardening is a heat process which alters the surface molecular structure of the steel. Rehardening an action can warp it. Subsequent efforts to straighten the metalwork, either by bending or filing can only harm the fine original metal-to-metal fit and adversely alter the workings of carefully aligned internal parts.

Cast Off
  • An offset of a gun stock to the right, so that the line of sight aligns comfortably with the right eye while the butt of the stock rests comfortably on the right shoulder. Almost all right-handed shooters benefit from a little castoff and most custom built guns are made this way. The only question is how much. The castoff of a gun is about right when, with the gun comfortably mounted, the front bead lines up with the center of the standing breech. A stock offset to the left, for shooting from the left shoulder is said to be Cast On.
Center Fire

Center Fire (Cartridge)

  • A cartridge with its primer located in the center of the base of the case.
  • A cartridge with a separate removable/replaceable detonating primer pressed into the center of its base---as opposed to a rimfire cartridge.
Center Of Mass
  • For self-defensive shooters, COM represents the area of an attackers torso within which the most vital organs are likely to be disrupted by a gunshot. Shooting to COM is considered the most expedient way to stop an assailant from continuing threatening behavior.
Centerfire Cartridge
  • A cartridge with a separate removable/replaceable detonating primer pressed into the center of its base---as opposed to a rimfire cartridge.
Chamber
  • An area at the breech end of a barrel, of about the diameter of the cartridge for which the gun was intended, and into which the cartridge is inserted. The nominal length of a shotgun chamber will accommodate the loaded cartridge for which it was intended and allow for its crimp to open fully when the cartridge is fired. Although one can easily insert a longer-than-nominal-length loaded cartridge in a shotgun chamber, it is not advisable to do so because when it is fired the crimp will open into the forcing cone. Because of the taper of the forcing cone, the crimp will not be able to open fully and the gun will develop far greater pressure than it was designed to handle.
  • The rear part of the barrel that is formed to accept the cartridge to be fired. A revolver employs a multi-chambered rotating cylinder separated from the stationary barrel.
Chamber Cast
  • To pour a low-melting-point material such as "Cerrosafe" into the chamber of a firearm, let it just cool, knock out the plug and measure it with a micrometer against published dimensional specifications to determine the chambering of a possibly-unmarked or possibly-altered firearm.
Chamber Depth Gauge
  • A cylindrical plug of hardened steel, precisely machined in relation to the standard dimensional specifications of a given cartridge, engraved with circumferential lines demarking the different typical lengths of cartridges available for that bore. By inserting the appropriate bore's plug-gauge into the chamber, one can read off the line indicating the nominal maximum length of the cartridge which should safely be able to be shot from that gun (provided, of course, the gun be in sound condition).
Chamber Throat

[cheym-ber]  [throht]

  • This is the area in the barrel that is directly forward of the chamber, which tapers to the bore diameter.
Charger
  • A simple, disposable narrow spring-lined channel-rail in which cartridges are supplied for military weapons. The shooter positions the clip vertically above the firearm's internal magazine, then pressing down with the thumb, slides the cartridges from the charger and down into the magazine..
  • A device typically made from stamped metal which holds a group of cartridges for easy and virtually simultaneous loading into the fixed magazine of a firearm.
Charger
  • A simple, disposable narrow spring-lined channel-rail in which cartridges are supplied for military weapons. The shooter positions the clip vertically above the firearm's internal magazine, then pressing down with the thumb, slides the cartridges from the charger and down into the magazine.
Checkered Butt
  • Checkering, applied to the otherwise-unfinished butt end of a gunstock
Checkering
  • A regular pattern of fine grooves cut into the surface of a stock to aid in gripping a gun. Originally done for utility only, checkering has become an art form in itself; craftsmen adorning the borders with ribbons, fleur-de-lys, floral carving, etc. The amount of coverage, the precise regularity, and the number of lines per inch indicate the quality of the work. Too-fine checkering, however, defeats the purpose of the work altogether.
Cheekpiece

(ˈtʃiːkˌpiːs)

  • A broad, flat, raised area on the side of a buttstock. While considered a sign of a well-appointed gun, it actually may interfere with natural mounting and pointing---somewhat negating the positive effect of cast-off. The cheekpiece is carved on the left side of a stock for a right-handed shooter; it is on the right side for a left-handed shooter.
Cherry
  • A rotary machine-tool cutting bit, in the precise shape of a specific bullet. Used for cutting the internal cavity of a bullet mold.
Choke

[chohk]  

  • A constriction at or near the muzzle of a shotgun barrel that affects shot dispersion.
  • A carefully measured constriction of the bore of a shotgun at the muzzle, designed to control the spread of the shot as it leaves the barrel
Choke Tubes
  • Short, interchangeable cylinders, of subtly different internal tapers, that screw into a threaded recess at the muzzle of a shotgun. By inserting different choke tubes, one can alter the shot pattern thrown by the gun. Choke tubes should be tightened until snug. Guns fitted for choke tubes should never be fired without tubes in place.
Chronograph

(krŏn′ə-grăf′, krō′nə-)

  • An device with a set of sensors through which a bullet is made to pass, connected to an electronic instrument which calculates bullet velocity.

 

Churchill Rib
  • A relatively tall, narrow, matted, solid, top rib on a pair of side-by-side barrels, developed by Robert Churchill.
Claw Extractor

(ĭk-străkt′)

  • An essential design element of the Mauser 98 bolt action and its derivatives: the Springfield '03 and the Winchester pre-'64 Model 70. A large, long extractor is mounted to and revolves around the bolt shaft---or more properly, remains stationary in the receiver raceway when the bolt revolves. This claw takes positive hold of the cartridge coming from the magazine and places it in the chamber when the bolt is closed. Then, when the bolt is opened, the claw, never having relinquished its grip on the rim of the cartridge, withdraws it from the chamber with absolute reliability. Lesser bolt actions have a small clip built into the bolt face which snaps over the chambered cartridge rim when the bolt is closed. While cheaper to manufacture, this system allows the possibility of the clip slipping back off the rim of the expanded spent case during extraction. Most experienced hunters prefer an action with a Mauser-type claw extractor for its reliability, especially when facing dangerous game.
Claw Mounts
  • A quick-detachable scope mounting system, popular in Germany and Austria. The front of the scope is fitted with a hook-shaped tentacle which is inserted into a slot in a fixed front scope base. The rear of the scope is fitted with another set of hook-shaped tentacles. When these are pressed sharply downwards into their opposing receptacles they snap into place, held by a spring-loaded clasp, locking the scope into position. When properly installed, claw mounts are generally considered the best quick-detachable system for scope mounting: the cleanest looking, the easiest to operate and the most accurate in returning to zero. But, it is not an off-the-shelf, bolt-on system; claw mounts must be custom-fitted by a skilled gunsmith
Clay Pigeon

[pij-uh n]

  • Originally, live pigeons were used as targets, but they were gradually replaced with clay disks and ultimately banned. Later clay has been replaced with more suitable raw materials.
Clearing

[kleer-ing]

  • Unloading a gun and double checking that it is unloaded or fixing a malfunction so that the gun is ready to fire again.
Clicks

[klik]

  • A unit of adjustment for a sight. Can be for Iron sights, Reflex Sights and Scopes

 

Clip

(klĭp)

A device for holding cartridges together, usually to facilitate loading. Widely used as a synonym for "magazine" (although most firearm authorities consider this substandard usage). Technically, a magazine has a feeding spring, a clip does not. A clip is a device that is used to store multiple rounds of ammunition together as a unit, ready for insertion into the magazine or cylinder of a firearm. This speeds up the process of loading and reloading the firearm as several rounds can be loaded at once, rather than one round being loaded at a time

Gun Magazine vs Clips
Gun Magazine vs Clips

           

           

           

           

           

           

           

           

           

           

           

           

           

           

           

           

           

Clip
  • A simple, disposable narrow spring-lined channel-rail in which cartridges are supplied for military weapons. The shooter positions the clip vertically above the firearm's magazine, then pressing down with the thumb, slides the cartridges from the clip and down into the magazine. (Stripper Clip)
Closed Bolt Firing System
  • A type of firearm in which the action is closed, with a cartridge in the chamber prior to firing. When the trigger is pressed the cartridge is fired, and the action cycles loading another cartridge into chamber and when firing is stopped the bolt remains closed and the chamber remains loaded.
Co Witness Sighting

[wit-nis]  [sahyt]  

  • The use of any iron sight mounted onto a rifle that is fitted with an optical sight as a primary sighting system. They come in two basic configurations, fixed or flip-up. The idea is that if you align your red dot and your iron sights you have a backup aiming system on the gun
Cock

[kok]

  • A firearm's exposed hammer.
  • To tension the mainspring of a gun in preparation for firing, such as by pulling back the external hammer, pulling back the slide of a pistol, or opening and closing the barrel(s) of a break-open gun.
  • The term referring to the action of manually drawing the hammer back against its spring until it becomes latched against the sear, or sometimes the trigger itself, arming the hammer to be released by a subsequent pull of the trigger. Some external hammers, and all internal hammers, may be cocked simply by pulling the trigger
Cocked And Locked
  • The practice of carrying a self-loading pistol with a round in the chamber, the hammer cocked and the safety engaged. (CONDITION ONE)
  • Proper condition for active carrying of a Colt 1911 pistol: a round in the chamber, the hammer cocked, and the thumb safety engaged. Somewhat unnerving to the uninitiated.
  • A state of readiness of a firearm. The hammer (or similar mechanism if there is no hammer) only needs to be released by the trigger to cause the gun to fire.
Cocked and Locked
Cocked and Locked

           

           

           

           

           

           

           

           

           

           

           

           

           

           

           

           

           

Cocker And De-Cocker
  • A type of action on a break-open gun or rifle where, in place of a traditional top tang safety, a somewhat more robust tab is fitted. Normally such a gun is carried in the field loaded, but with the action not cocked---an exceedingly safe condition. Then, when ready to fire, the shooter, instead of pushing a safety tab forward, pushes this larger tab forward, cocking the mainspring, making the gun ready to fire. Then, if the shot is not taken, he may simply slide this tab rearwards again, de-cocking the gun and returning it to the still-loaded, but very safe position. Or, in German: Handspanner.
Cocking Indicators
  • Small devices attached to the internal hammers of a break-open gun and visible from the exterior of the gun to show when each lock is cocked and when it has been fired. These are usually in the form of protruding pins on a boxlock gun or in the form of engraved or gold inlaid lines on the tumbler pins of a sidelock gun
Coin Finish
  • Generally refers to a high-polish finish, bright steel on the receiver of a break-open gun. Other action-body finishes could be case-hardened, blued or French-gray (a chemical-finish, dull gray steel color). Coin-finish, when appearing typically on a modern, high grade Italian shotgun shows off the exquisite and delicate engraving better than other finishes. The term is sometimes used (incorrectly) by people dealing in old guns to describe the finish on a well-worn gun’s receiver when all the original case-hardening colors have worn or have been polished off.
Cold Clean Bore
  • The first shot from a rifle that has been cleaned, and not fired recently may go to a different point of impact, for the same point of aim than a rifle that has been fired recently. This first shot is referred to as a shot from a cold, clean, bore.
Cold Range
  • Pistol and or any firearm must be unloaded until it is your turn to shoot
Collapsible Stock

or collapsable [kuh-lap-suh-buh l]

  • A stock on a long gun that can be shoved into itself to shorten it, either for storage or to make the gun fit shooters of different sizes.
Collimator

(kŏl′ə-mā′tər)

  • An optical device, mounted to the muzzle of a rifle via a bore-sized mandrel, the purpose of which is to allow a reasonable approximation of correct sight adjustment before actually firing live ammunition
Comb
  • The top of a gun's stock, where a shooter rests his cheek when mounting a gun. As it is the top of the stock that determines the position of one's eye, and one's eye is the rear sight on a shotgun, the position of the comb is very important in determining the proper fit of a shotgun.
Combination Gun
  • A firearm with various different configurations of rifle and shotgun barrels. See various specific types: BockbüchesflinteCape GunParadox,  DrillingDoppelbuches-DrillingVierling,
Commemorative

 (kə-mĕm′ər-ə-tĭv, -ə-rā′-)

  • In firearms parlance, a gun that was manufactured in "limited" numbers (often into the thousands), marked, stamped or fitted with extra bells and whistles in such a way as to evoke reverence to some famous person, place or historical event. Rather than to be manufactured for honest use, a commemorative is manufactured specifically to be collected. Actually to shoot one will normally delete any supposed extra value such a questionable concept ever had in the first place.
Compensator

[kom-puh n-seyt]

  • Also call a Muzzle Brake. A device attached to or made as part of a firearms barrel designed to reduce recoil or muzzle movement on firing. They generally increase muzzle blast. The may also, but not necessarily so, diminish muzzle flash.
  • A cylindrical muzzle extension, with slots on the top, designed to push the muzzle down when a gun is fired, counteracting its tendency to rise

 

Concealed

[kuh n-seel]

  • verb (used with object) to hide; withdraw or remove from observation; cover or keep from sight: He concealed the gun under his coat.
  • Hidden from view. A handgun is concealed when it is carried in such a manner that is unseen

   

Concealed Third Fastener
  • An extension protruding rearward from the breech end of a set of side-by-side barrels and entering a complementary recess in the breech face. The top of the extension is locked down by a cam attached to the toplever spindle. When the gun is closed this extra fastener is not visible from the exterior of the gun. Also called a Secret Bite.
Condition One

Condition One, etc

(kən-dĭsh′ən)   (wŭn)

A system devised by Jeff Cooper for enumerating carry modes for the Colt 1911 and similar auto pistols. Condition One is cocked and locked; Condition Two is hammer down with a round in the chamber; Condition Three is with a loaded magazine, empty chamber; Condition Zero is with a round in the chamber, hammer cocked, safety disengaged.

Colt Delta Elite
Colt Delta Elite

           

           

           

           

           

           

           

           

           

           

           

           

           

           

           

           

           

Controlled Feed
  • Aspect of the design of the Mauser 98 bolt action and its derivatives: the Springfield '03 and the Winchester pre-'64 Model 70. A large, long extractor is mounted to and revolves around the bolt shaft---or more properly, remains stationary in the receiver raceway when the bolt revolves. This claw takes positive hold of the cartridge coming from the magazine and places it in the chamber when the bolt is closed. Then, when the bolt is opened, the claw, never having relinquished its grip on the rim of the cartridge, withdraws it from the chamber with absolute reliability. Lesser bolt actions have a small clip built into the bolt face which snaps over the chambered cartridge rim when the bolt is closed. While cheaper to manufacture, this system allows the possibility of the clip slipping back off the rim of the expanded spent case during extraction. Most experienced hunters prefer an action with a Mauser-type claw extractor for its reliability, especially when facing dangerous game.
Controlled Pair
  • Two shots fired in rapid succession. It is different from a double tap because in a controlled pair, the second shot will be fired after the shooter has obtained a second sight picture, whereas in a double tap both shots are fired based upon the initial sight picture alone.
Cordite

(kôr′dīt′)

  • An early form of smokeless powder, developed in England in the late 1880s, taking the physical form of little strings---or cords. Unlike black powder which preceded it, it burned a bit more slowly, enabling pressure to build in a barrel more evenly, increasing the duration of the motive force, increasing its efficiency propelling the projectile down the bore to higher velocities. And, it didn't generate nearly as much smoke---which hitherto both obscured the vision of the shooter while revealing his position to an adversary.
Counterbored Cylinder
  • In Smith & Wesson parlance, Recessed
Cover

[kuhv-er] verb

  • To protect or conceal
  • Take cover, to seek shelter or safety
  • Anything an intended victim hides behind that will probably stop a bullet.
Cover Garment
  • Any piece of clothing that covers the holstered gun. When the gun is worn on the belt, the most common types of cover garments are vests, sweaters, and jackets.
Cowboy Action Shooting

[kou-boi] [ak-shuh n] [shoot]

Cowboy Action Shooting (CAS, also known as Western Action Shooting, Single Action Shooting, or Cowboy 3-Gun) is a competitive shooting sport that originated in Southern California, US, in the early 1980s. Cowboy action shooting is now practiced in many places with several sanctioning organizations including the Single Action Shooting Society (SASS), Western Action Shootists Association (WASA), and National Congress of Old West Shooters (NCOWS), as well as others in the US and in other countries.

CAS is a type of multi-gun match utilizing a combination of pistol(s), rifle, and/or shotgun in a variety of "old west themed" courses of fire for time and accuracy. Participants must dress in appropriate theme or era "costume" as well as use gear and accessories as mandated by the respective sanctioning group rules.

Crane

(krān)

The swinging unit that hinges the cylinder of a revolver with the frame.

Revolver Crane
Revolver Crane

           

           

           

           

           

           

           

           

           

           

Creedmoor
  • Site, from 1872 until 1912, in Queens, Long Island, of the National Rifle Association's first national matches. Name used by several rifle makers to invoke the concept of accuracy in their products.
Creep
  • Sloppy, indeterminate movement of a trigger before the actual point of let-off.
Crescent Buttplate
  • A sturdy, cast metal buttplate fitted particularly to many early lever-action rifles with a deep curve in the center of the butt, durable under rough use, but uncomfortable in use and extremely painful when carelessly mounting and firing a powerful rifle.
Crimp
  • The star-shaped folded closure at the mouth of a shotgun shell. The nominal length of the cartridge is measured with the crimp open---for which the gun's chamber must be long enough to accommodate
Cross Dominant
  • This means a shooter who is right-handed but left-eyed, or left-handed and right-eyed.
Cross Eyed or Crossover Stock
  • A gunstock with extreme cast (Cast-off or Cast-on), usually custom made, for use by persons with disability so as to be able to shoot from the right shoulder using the left eye (or from the left shoulder using the right eye). Or, for a right-handed shooter with a left master eye.
Cross Pin Fastener
  • A horizontal wedge, press-fit through the forend of a vintage gun, through a lump attached to the underside of the barrel and out the other side of the forend. To secure the forend in position. Also called a key fastener.
Crossbolt

[′krȯs‚bōlt]

  • A steel bolt, mounted transversely through a rifle stock just under and behind the front (and sometimes rear) receiver ring, sometimes concealed in the wood and usually against which the action is carefully bedded. When properly fitted, it helps distribute the recoil and reinforces stock at the point where wood has been removed to accept the action. Recoil crossbolts can be recognized by the flush-mounted circular steel fittings on the side of the stock, but are sometimes finished with contrasting wooden plugs and sometimes concealed completely. Also called Reinforcing Crossbolt.
Crosshairs

ˈkrôsherz/

  • The cross-shaped object seen in the center of a firearm scope. Its more-proper name is reticle.
  • Basic form of telescopic sight reticle, having one fine vertical line and one fine horizontal line with which to establish the point of aim.
Crown
  • The area inside the bore nearest the muzzle. Damage to the crown can severely and adversely affect the firearm's accuracy.
  • The finish contour of the muzzle of a rifle. May be flat or rounded. Often shows effective chamfering to protect the critical rifling at the absolute end of the muzzle
CUP

C.U.P

Copper Units of Pressure. The units by which cartridge breech pressures are measured through compression of a copper crusher gauge. Similar but not identical to the older pounds per square inch (psi) system of measurement. Copper units of pressure or CUP, and the related lead units of pressure or LUP, are terms applied to pressure measurements used in the field of internal ballistics for the estimation of chamber pressures in firearms.

C.U.P. vs PSI C.U.P. vs PSI                                                                         Copper Units of Pressure Copper Units of Pressure

Curios or Relics
  • Is defined in 27 CFR 178.11 as follows:"Firearms which are of special interest to collectors by reason of some quality other than is associated with firearms intended for sporting use or as offensive or defensive weapons. To be recognized as curios or relics, firearms must fall within one of the following categories:
    1. Firearms which were manufactured at least 50 years prior to the current date, but not including replicas thereof;
    2. Firearms which are certified by the curator of a municipal, State, or Federal museum which exhibits firearms to be curios or relics of museum interest; and
    3. Any other firearms which derive a substantial part of their monetary value from the fact that they are novel, rare, bizarre, or because of their association with some historical figure, period, or event. Proof of qualification of a particular firearm under this category may be established by evidence of present value and evidence that like firearms are not available except as collector's items, or that the value of like firearms available in ordinary channels is substantially less."
A list of acknowledged "Curios or Relics" is available from the Bureau of Alcohol, Tobacco and Firearms, Firearms Technology Branch, Room 6450, 650 Massachusetts Avenue NW, Washington, DC 20226

A special Curios or Relics license is available from the BATF, which allows collectors to buy eligible firearms in interstate commerce. A licensed collector is not authorized to engage in business as a dealer in any firearms, including curios or relics.

Cut Away
  • A firearm that has had numerous careful machining cuts taken in its exterior with a view to exposing and demonstrating the functioning of critical parts of its mechanism
Cutts Compensator
  • A cylindrical muzzle extension, with slots on the top, designed to push the muzzle down when a gun is fired, counteracting its tendency to rise.
Cylinder

[sil-in-der]

  • That part of a modern revolver that holds cartridges in separate chambers radially around a central hingepin. The cylinder revolves as the handgun is cocked, bringing each successive cartridge into position, and locked into alignment with the barrel for firing.
  • A rotating cartridge holder in a revolver. The cartridges are held in the chambers and the cylinder turns, either to the left or to the right depending on the gun maker's design, as the hammer is cocked.
  • A shotgun barrel with no choke constriction at the muzzle.
Cylinder Drum

[sil-in-der]   [druhm]

  • On a revolver, a spring activated device housed in the bottom of the frame beneath the cylinder that engages alignment notches in the cylinder. It stops the cylinder's rotation and holds it in place each time a chamber in the cylinder is in alignment with the barrel.